In the xy-plane, the region y > 0 has a uniform magnetic field $$B_{1} \hat{k}$$ and the region y < 0 has another uniform magnetic field $$B_{2} \hat{k}$$. A positively charged particle is projected from the origin along the positive y-axis with speed $$v_{0} = \pi m s^{-1}$$ and t = 0 as shown in the figure.Neglect gravity in this problem. Let $$t = T$$ be the time when the particle crosses the x-axis from below for the first time. If $$B_2 = 4B_1$$, the average speed of the particle, in $$ m s^{-1}$$, along the x-axis in the time interval T is __________.